The present invention relates to a contact member including a coating formed on a portion that is, or can be, contacted with an optical disk in an optical disk apparatus for reading and recording the optical disk, a protecting film for the optical disk and a coating composition that can form the film.
In recent years, various types of optical disks have been developed. Two types are widely known. One type is that the optical disk itself is inserted into the optical disk apparatus such as a CD, a DVD and the like. The other type is that the optical disk contained in a case is inserted into the optical disk apparatus such as an MO, an MD, a DVD-RAM and the like.
The former type that the optical disk itself is inserted into the optical disk apparatus has a problem that a recording surface of the optical disk such as the CD and the DVD may be abraded and damaged at a disk insertion. When the optical disk is impacted accidentally during the CD or DVD reading or recording, an objective lens or the recording surface of the optical disk may be damaged.
The optical disk apparatus having a property to collect light using the same lens as to the CD and the DVD has a problem that the objective lens collides with the optical disk due to a difference in a working distance. The objective lens or the recording surface of the optical disk may be damaged.
A helium neon laser that can record more information has been developed instead of the conventional semiconductor laser. The use of the helium neon laser makes the space between the objective lens and the optical disk very narrow. Accordingly, the objective lens collides with the optical disk depending on accuracy of the optical disk itself, or due to deflection upon operation of the optical disk. The objective lens or the recording surface of the optical disk may be damaged.
Various attempts have been made to solve the above-mentioned problem that the objective lens or the recording surface of the optical disk may be damaged in the optical disk apparatus. For example, Japanese Patent Laid-Open Application No. 2-54433 describes that a pick-up actuator moving part nearest to the optical disk is made with a softer material than that of the optical disk. Japanese Patent Laid-Open Application No. 11-312322 describes that a silicone rubber protector is applied around the objective lens. Japanese Patent No. 2593998 describes that a cushioning material such as a sheep felt and the like are applied around the objective lens. Japanese Patent Laid-Open Application No. 2000-242958 describes that an elastic body, i.e., rubber is applied to the objective lens itself.
However, in the DVD and the optical disk using the helium neon laser, the damaged recording surface of the optical disk or the damaged objective lens may adversely affect reading properties of the optical disk than ever before. For example, even though a tray and the disk insertion of the optical disk apparatus are made of a polyacetal resin that is softer material than that of the optical disk, it is difficult to completely prevent scratches that may adversely affect the reading properties of the recording surface of the optical disk.
The cushioning material such as the polyacetal resin, the rubber and the felt suffer from significant creep or elastic deformation. It is therefore difficult to completely prevent the collision of the objective lens and the optical disk.